I recently bought a 94 Aerostar regular length AWD 56000 miles. It has the 4.0, the van runs good but did have a few problems when I bought it. It had a very minor leak in the radiator at the lower seam, needed the tranny, tranaxle fluid changed. A new serpentine belt. The power steering pump makes the whaaa sound and it did not idle smooth. Took it to my mechanic who I trust completely and had him put a new belt on, change the fluids and check the power steering pump and the radiator. By the way before I took it in I installed new plugs, wires and PVC valve. The plugs and wires were a trip to hell and back and my hands are still healing up. (Ha Ha) This helped the idle problem only a little. I also cleaned the throttle body and MAF before I took it in to him. He called and said everything was OK on the van and preceded to tell me that the Ford 4.0 motors do not idle real smooth and that a complete fuel system cleaning with some kind of machine would help. I gave the OK, got the van back and it did help a little, but still not real smooth at idle. So my question is not ever owning a Ford 4.0, are they supposed to idle smooth or is this just the way they are? If they are supposed to idle smooth, what else should I check or have checked out? Also he said the power steering pump noise is normal and that 1 out of 5 he replaces helps the noise a little, that the pump was fine and full of fluid no leaks just noisey. Thanks

 

Well, my '91 Ranger with the 4.0L is real smooth. One of the smoothest running engines I've seen. However, my '95 Aerostar has a slightly rough idle when warm and if you listen to the exhaust it sounds kind of like a lean miss. During warmup, it runs really smoothly so I think that the idle can be improved so that it is as smooth as my Ranger. I went through the same things you did with the fuel injector cleaner, plugs, wires, etc. only to make minor improvements. It appears to me (and to the mechanic who ran the fuel injector cleaner through the engine) that the fuel injectors are at least partiallly plugged on my Aerostar. So, I will be pulling them off and having them cleaned (I hope the mechanic's diagnostics were correct because pulling the injectors will be a pain). The fuel injector cleaner works well as a maintenance item to keep the injectors clean but once they're plugged, the only way to get them cleaned is to removed them and have them ultrasonically cleaned.

As far as the power steering pump goes, mine has been whining since I bought it over a year ago (it had 56K on it at the time) and there are no signs of trouble with 68K now on it. The one on my Ranger doesn't whine but I've heard that the whining usually isn't indicative of a problem so I'm not going to be replacing my Aerostar's pump any time soon.

A tip for changing the plugs would be to go buy yourself one of those ratchets that have a swiveling head, it helped tremendously for me (saves about 1.5 hours).

 

Thanks for the reply. Is there a problem with the injectors on these. The reason I ask, I have owned alot of fuel injected cars with alot of miles on them and never had a clogged injector. Have you ever cleaned or replaced the Idle Air Control Valve? I have read these get dirty and cause problems. I will be doing this, this weekend. If it is the injectors I probably won't do it myself or pay high dollar to have it done. I will post back after checking the control valve and let you know. Thanks again.

 

Hi, I had an 89 aerostar that had dirty injectors they didn't say if they were plugged or not it was still under warranty so ford cleaned them but they told me to run good gas in it not the no-name cheapie brand because they will plug the injectors. it is the bottom of the barrel all names that they use so anything that settles is going to that station and into your car.
JOHN(FATFORTY)

 

Had the same problem on my '93 Aerostar with the 3 liter engine. Idle at 850 rpm was not as smooth as I'd like it. I simply raised the idle speed to 950 rpm. Now she runs very smooth.

 

As far as the injectors go, everyone I talked to is surprised that I would have a problem with them with only 67K on them. It is uncommon for the 4.0, however, it does happen, especially with bad gas. One piece of evidence that further reinforces that the injectors might be plugged on my Aerostar is the fact that I sawed open the fuel filter when I changed it. It was really dirty compared to the filter on my Ranger (both changed at the same time with almost the same mileage). I found a place that will clean the injectors for a reasonable price so I will give that a shot. I'm not too worried about the cost as I will be doing all of the work (except the cleaning, of course) myself.

Your problem could also be due to a vacuum leak around one of the fuel injector o-rings or a vacuum leak in some other location (intake gasket, etc.) so you should probably check that out as well.

As far as the idle air control valve, that was one of the first things that I checked and it was clean but it's a good idea to check it.

 

I have a 93 AWD Aerostar with the 4.0, 114,000 miles and it uses one quart of oil quart every 800 miles (leaking intake manifold) and it runs smooth. The only time it runs rough is on a very hot day (90+ degrees) when it is cranked after being driven for awhile. it than smoothes out in a couple of seconds. Sounds like dirty fuel injectors?Try some of the good cleaner if you haven't.
Avanti John
93 Aerostar AWD ext
92 F150 XLT ext cab
89 Bronco II XLT
64 Avanti

 

I have a 93 4.0 with 123000 on it. it idles smooth as can be, and has never had the injectors cleaned. Before I went down that road I would check the vacuum hoses to the heater, cruise, etc. There is a manifold that the vacuum hoses comes off of on the right bank(looking from front to rear) close to the back. these hoses can become swelled and loose from oil, heat, and other contaminants. I would check there first. It's cheap and not too painful.

 

I think I finally figured out the problem. Since I bought the van 11/20/00 it has never made it up to the first line on the temp guage. When it started getting cold here I noticed the heat was only very warm. I bought a new thermostat and went to put it in last Saturday (forgetaboutit) I knew once I started I was never going to be able to acomplish this. Gave up early in the game and called my mechanic and took it in Monday and had him suffer and do it. Went to pick it up and he imediately started bitching about it.(HA HA) Anyway 62.00 later (By the way the most I ever spent to have a thermostat replaced) that was when I started bitching back. Anyway took the van for a drive, temp guage goes up half way and excellent heat. It has done nothing but run better the more I drive it since the thermostat has been changed. Hard telling how long it had been stuck open. I trully believe this has been the idle problem all along!!!

 

Yeah, those thermostats are tough on them, but wait till you do a waterpump or a trans. although spark plugs are no picnic either.LOL good luck with it!!!! John

 

I just sold a 94 Ranger with the 4.0 and it was a great truck. Hated to sell it as a matter of fact. Had 79K on it . Never used any oil , ran perfectly at all RPM's. Never a moments trouble. The person I sold it to loves it.

 

How do you increase the idle speed?